YAP and TAZ are transcriptional co-activators of AP-1 proteins and STAT3 during breast cellular transformation (ChIP-seq)

The YAP and TAZ paralogues, the ultimate effectors of the Hippo signaling pathway, are deregulated in many cancer types. They are transcriptional co-activators that are recruited to their target sites, primarily by TEAD proteins. Here, we show that YAP and TAZ are also recruited by JUNB and STAT3, key factors that mediate an epigenetic switch linking inflammation to breast cellular transformation. YAP and TAZ directly interact with JUNB and STAT3 via a WW domain that is important for transformation, co-occupy many target sites in vivo via the sequence motifs of AP-1 and (to a lesser extent) STAT3, and stimulate transcriptional activation by AP-1 proteins. A small minority of target sites are YAP- or TAZ-specific, and they are associated with different sequence motifs and gene classes. YAP/TAZ, JUNB, and STAT3 directly regulate a common set of target genes that overlap, but are distinct from, those regulated by YAP/TAZ and TEADs. The set of target genes regulated by YAP/TAZ, STAT3, and JUNB is associated with poor survival in breast cancer patients with the triple-negative form of the disease. Overall design: YAP/TAZ, AP-1 and STAT3 transcriptional regulation in breast cancer